Clark Green and Reggie Duncan have similar size, speed and running styles.

Kansas University football coaches have pointed out key differences in the running backs during preseason camp, saying Green, a red-shirt freshman, was a better blocker and receiver than Duncan, the incumbent starter.

Duncan, however, has proven more durable than his young challenger.

“He really looks sharp,” KU coach Mark Mangino said Tuesday. “He has not been hindered by any of the bumps or bruises that normally come along with two-a-days. He’s been able to get through that pretty good.”

Green has not.

Mangino doesn’t discuss specific injuries with reporters, but the coach said Green (5-foot-11, 200 pounds) has been hobbled in recent practices. That opened the door for Duncan (5-9, 215), a junior who had been battling the red-shirt freshman since spring drills.

When full-squad, two-a-day practices began on Aug. 10, it appeared Green might have an edge. Running backs coach Clint Bowen and Mangino both challenged Duncan after the back struggled in the heat and humidity.

“He responds well to challenges, so we just pose one for him every day,” Mangino said with a smile.

Duncan has taken command of the position 10 days before the Aug. 31 season opener at Iowa State.

“It looks like Reggie’s going to be the guy on opening day,” said Mangino, whose team concludes two-a-day practices tonight with an open workout at Memorial Stadium. “We can’t discount Clark Green. It’s just that he’s had a bunch of nagging injuries that have held him back. Reggie’s been durable and going every day. Clark’s been practicing, but he doesn’t always have the ability to go full speed.”

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QB battle continues: Mangino hasn’t named his starting quarterback yet, though junior Zach Dyer (6-2, 200) is No. 1 on the depth chart.

“I won’t make the call on quarterback yet because I’m not really sure that’s the way it’ll play out,” Mangino said.

Dyer clearly has the edge, though. The Olathe South graduate is taking the majority of the snaps with the No. 1 offense. Junior college transfer Bill Whittemore (6-0, 200) has been working with the first- and second-string units, and senior Jonas Weatherbie (6-2, 200) has primarily worked with the second string.

KU is expected to release an updated depth chart on Thursday.

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Check your roster: Red-shirt freshmen Ronnie and Donnie Amadi have worked their way onto the two-deep chart at cornerback. Donnie is battling sophomore Leo Bookman for the starting job at one corner, while Ronnie is listed as a backup to junior Remuise Johnson at the other.

Ronnie (5-11, 175) is an inch taller than Donnie (5-10, 175), but the Alief, Texas, natives still are a mystery to their teammates. How do coaches know one from the other?

“Jersey numbers,” Mangino said. “We struggle. Coaches that have been here a few years don’t know them apart.”

For the record, Ronnie is No. 17, while Donnie wears No. 26.

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Reid ready: Count Nick Reid (6-4, 210) among the true freshmen who have a chance to play this season. The Derby graduate started camp as a quarterback before moving to safety.

“He has just been outstanding,” Mangino said of Reid, who was a three-sport standout at Derby High. “There’s a very good chance he’ll see time from the line of scrimmage and probably on all the special teams. He’s an excellent athlete, but he’s also a very intelligent guy. He really understands everything we’re teaching. For a guy that didn’t have spring ball, he’s doing very well.”

Mangino also has mentioned receivers Mark Simmons, Charles Gordon, Jerome Lewis and defensive end Kyle Knighton as true freshmen who might play this fall.

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Teddleton in the mix: Junior nose tackle Brock Teddleton was listed No. 1 on the preseason depth chart but was knocked off the two-deep list by red-shirt freshman Tim Allen and junior college transfer Sid Bachmann.

Mangino said Teddleton’s fall was unrelated to his Sept. 18 trial date in a misdemeanor battery case.

“He was demoted,” Mangino said. “Since he’s been demoted he’s been the most focused and working harder than he ever has in any point in our program. He’s working his way back up. He really is.”

And what about that trial date?

“He’s entitled to due process,” Mangino said. “I’ll handle it accordingly.”